Optical measuring systems utilizing light from a laser beam are known. One such system is the co-pending application, Ser. No. 566,413, for "Reticle Calibrated Diameter Gauge," by David E. Harris, et al., now U.S. Pat. No. 4,043,673 and assigned to the same assignee. In that co-pending system the occultation of the measuring beam by the object being measured generates a signal operative to control counting of the calibration pulses as an indication of the dimension being measured.
There are many other variations of the split beam reference/measuring signal comparison variations known to the prior art.
Each of the prior art optical measuring systems, although perhaps operable for their intended purpose, do have attendant disadvantages. These prior art systems generally utilize, for instance, a scanned photo diode matrix or complex vidicon. Particularly, the need for calibration and constant recalibration, incapacity for a low measurement rate, high resolution capabilities, in stability, accuracy, and dependence from surface color and composition errors have been encountered with these prior art optical measuring systems. These disadvantages in turn are reflected as tremendously costly.